Single stroke control system and fluid control unit therefor



Oct. 17, 1961 E. H. ANDRUS ETAL SINGLE STROKE CONTROL SYSTEM AND FLUIDCONTROL UNIT THEREFOR 5 Sheets-Sheet 1 Filed March 20, 1959 (spring-s61.1L8 1L8 2L8 air-released) EVERETT H. ANDRUS lg, 2 AND GEORGE M. COONflak/ATTORNEY.

Oct. 17, 1961 Y E. H. ANDRUS ET AL 3, 7

SINGLE STROKE CONTROL SYSTEM AND FLUID CONTROL UNIT THEREFOR Filed March20, 1959 5 Sheets-Sheet 2 4 1 V EM? INVENTORS.

EVERETT H. ANDRUS AND GEORGE M. COON 7 u why/QM f ATTOR NEY.

Oct. 17, 1961 E. H. ANDRUS ETAL SINGLE STROKE CONTROL SYSTEM AND FLUIDCONTROL UNIT THEREFOR Filed March 20, 1959 5 Sheets-Sheet 3 INVENTORS.

EVERETT H. ANDRUS BY AND GEORGE M. COON U. ATTORNEY.

Oct. 17, 1961 E. H. ANDRUS ETAL SINGLE STROKE CONTROL SYSTEM AND FLUIDCONTROL UNIT THEREFOR Filed March 20, 1959 5 Sheets-Sheet 4 HOV.

\ Ell II I INVENTORS.

EVERETT H. ANDRUS AND GEORGE M. COON MATTQRNEY.

Oct. 17, 1961 E H. ANDRUS ETAL 3,004,647

SINGLE STROKE CONTROL SYSTEM AND FLUID CONTROL UNIT THEREFOR Filed March20, 1959 5 Sheets-Sheet 5 IIOV INVENTORS. EVERETT H. ANDRUS BY ANDGEORGE M. COON ATTORNEY United States Patent 3,004,647 SINGLE STROKECONTROL SYSTEM AND FLUID CONTROL UNIT THEREFOR Everett H. Andrus, Berea,and George M. Coon, South Euclid, Ohio, assignors to Textrol, Inc.,Cleveland,

Ohio

Filed Mar. 20, 1959, Ser- No. 800,894 28 Claims. (Cl. 192-142 Thisinvention relates to improvements in a single cycle control for amachine.

Many types of machines used in industry are so inherently dangerous thattheir operation must be limited to a single stroke at a time. Examplesof such machines are punch presses, power-operated cutters, and othermachines capable of seriously injuring the, operator if he happens tohave his fingers or any other part of his body in the way of the movingparts of the machine.

Various two-hand start controls have been proposed heretofore whichrequire that the operator have both hands out of the way before he canstart the machine. Commonly, such two-hand start controls comprise apair of spaced switches which must be actuated by the respective handsof the operator either simultaneously or within a predetermined intervalof one another in order to start the machine. Such safety controls havebeen generally satisfactory for their limited purpose, which is toinsure that the operator himself cannot cause a stroke of the machineexcept by moving his hands out of the way to operate the switches.

Various controls have been devised whose purpose is to stop the machineautomatically at the end of each stroke. Many such controls incorporatethe two-hand start principle just described. However, in all suchcont-rols heretofore the malfunctioning of a single compo: nent in thecontrol may permit the machine to go through repeated cycles ofoperation. Because the operator is not expecting this, he may have hishands in a dangerous position, particularly since he will have developeda certain rhythm of movement in operating the machine.

Such failures in the controls themselves, involving no fault of theoperator of the machine, have resulted in rather frequent and seriousaccidents whose toll in human misery and monetary damage is immense.

The present invention is directed to a novel control for such machineswhich reduces thepossibleoccurrence of an unexpected repeat stroke, ofthe machine toI a virtual. mathematical impossibility. In the preferredem.- bodiment of this invention, such optimum reliability is obtained byproviding a unified control which includes every component involved incontrolling the operation of the machine. Failure of any one of thesecomponents will prevent the next stroke of the machine from takingplace. Moreover, in the present system each component has a counterpartwhich independently performs the same control function. Therefore, forthe;system to fail, it would be necessary for two control components tofail at the same time. Thus, if the probability of failure of aparticular control component, such as a valve, relay or switch, is onein 1,000,000 operations, the probability that two control componentswill fail at the same time is reduced to one in 1,000,000,0 00000.

In addition to the dual arrangement of control components, the presentsystem automatically monitors the performance ofeach component duringeach cycle of operation of the machine. Should any individual componentfail to perform properly, the operator cannot start the next stroke ofthe machine. Therefore, the'greatly enhanced protection providedby thedual system cannot be lost by an undetected failure of any singlecomponent inthesystem.

3,004,647 Patented Oct. 17, 1961 It is an object of the presentinvention'to provide a 7 novel and improved control system for amachine.

It is also an object of this invention to provide a novel control systemfor limiting a machine to a single cycle of operation at a time, whichsystem is more reliable in operation than prior systems for the samepurpose.

Another object of this invention is to provide a novel single strokecontrol system for a machine in which the performance of each componentof the control system is monitored during each cycle of operation of themachine, so that upon failure of any component the next cycle ofoperation of the machine cannot be initiated.

A further object of this invention is to provide a novel control forautomatically limiting a machine to a single stroke which may be usedwith any suitable control arrangement intended to restrict the operatorto single stroke operation of the machine, so that the complete systemis substantially foolproof in operation, whether in the event of failurein the automatic control or in the event the operator attempts to beat"the control.

Another aspect of this invention is concerned with a fluid control unitfor controlling the application of fluid pressure to start or stop themachine. While this fluid control unit is extremely important to thesuccessful operation of the present control system, it is not limited inits utility to the present system, but may also be used in other controlsystems for the same general purpose to provide a monitored dual controlover the application of fluid pressure to start or stop the machine.

Therefore, it is also an object of this invention to provide a novelfluid control unit for use in a single stroke control system for amachine.

Further objects and advantages of the present invention will be apparentfrom the following detailed description of a presently preferredembodiment thereof, which is illustrated in the accompanying drawings.

Inthe drawings:

FIGURE 1 shows schematically the drive arrangement for the crankshaft ofa machine, together with the airoperated control for starting andstopping the crankshaft and the various limit switches operated duringthe stroke of the crankshaft;

FIGURE 2 shows the condition of these limit switche at various timesduring the stroke of the crankshaft, each shaded portion indicating thatthe switch is closed and each unshaded portion indicating that theswitch is open;

FIGURE 3 is a schematic diagram of one embodiment of the electricalcircuit in the present control system;

FIGURE 4 is a section through one valve unit in the present invention; a

FIGURE 4A is a section along the line A-A in FIG. 4 through the pilotvalve;

FIGURE 5 is a schematic diagram of a second embodiment of the electricalcircuit in the present control system; and ;.-FIGURE 6 is a schematicdiagram of a third embodiment of the electrical circuit in the presentcontrol systern, this being the preferred embodiment.

Referring first to FIG. 1, the rotary crankshaft 20 of the machine isconnected through a clutch 21 to a continuously operating drive motor22. The machine itself maybe a punch press or any other machine intendedto have single strokeoperation for the operators safety. Normally, inthe absence of air pressure in line 23-, the clutch is disconnected sothat the motor 22, even though energized, does not drive the crankshaft20. The crankshaft also is provided with a brake 24 which is spring-setto lock the crankshaft against movement. However, when air pressureappears in line 23, the brake is'released.

The crankshaft carries a series of cams 25, 26 and 27 p which controlthe operation of limit switches ILS lLSg and 2L8, respectively.

shown in FIG. 2, both of the switches lLS and lLS are closed throughoutslightly more than the first half of the rotation of crankshaft 20. Boththese switches open at approximately 185 of the crankshaft rotation andclose again about 30 later. p

Switch 2L8 is open from to about 175 or the crankshaftrotation and isclosed from 175 to about 330 at which time it opens.

Coupled to the crankshaft 20 is a sprocket 28' which drives a chain 29,-which drive's a sprocket 30 connected to a rotary shaft 31. A- pair ofearns 32 and 33 are mounted on shaft- 3 1 to turn therewith. Gain 320pera't'es a limit switch IRS,- while earn 33 operates a limit switch2R8.

As shown in 2, switch IRS is closed from 0 to about 305 of rotation ofthe crankshaft, is open from 305 to about 335, at which time it closesand remains closed through the remainder of the cycle.

Switch 2R8 is open rrom 0 to about 175, is closed from 175 to about 330,and is open from 330 to the end of the cycle. I i

The air'sup'ply to line 23 for releasing the brake 24- and connectingthe clutch 2 1 is under the joint control of the fluid control unitwhich forms part of the present invention; This fluid control unit'-(shown in FIG; 4 and described in detail hereinafter) comprises a pairof poppet valves 33 and 34 which are coli'nec'ted in series iii the airline between the air inlet 35 and line 23. Poppet valve 33 is tinder thecontrol of a pilot valve 36 operated by solenoid K Similarly, poppetValve 34 is 'under the central of a pilot valve 37 operated by solenoidK Each of the pilot valves is normally open and each has its inletconnected to the air inl'ct line 35 ahead of the first poppetvalve 33,through separate lines 38 and 39, respectively. The outlet line 40 frompilot valve 36 is connected to the poppet chamber in valve 33- tomaintain valve 33 closed nonnally, i.e., when pilot valve 36 is open.Similarly, the outlet line 41 from pilot valve 37 is con nected to thepoppet chamber in valve 34 to maintain valve 34 closed when pilot valve37 is open; I

I When solenoid K is energized, it closes pilotvalve 36 and the firstpoppet valve 33 opens.

When solenoid K is energized, it closes pilot valve '37 and poppet valve34 opens. v

The first poppet valve 33 is provided with a plunger 42 connected to themovable valve elenient in this valve and projecting beyond the valvecasing. Plunger 42 opcrates a pair of switches 1VS and 1VS Theseswitches are incor orated in adouble-pole switch unit of known constuction, Normally (i.e., with pilot valve 36 open and poppet valve asclosed) the plunger is in its extended position beyond the salve casingand maintains switch IVSg closed and switch IVS open, When poppet Valve33 opens, in response to the energizatiofi of solenoid K and the closingof pilot valve 36, as described, the plunger 42 is retracted and switchIVSg opens and, switch In like manner, the second poppet valve 34 isrovided with a plunger 43 which operates a pair of switches TZVSg andZVS Normally (lie, when poppet valve 34 is closed the plunger 43 is iiiits extended position rnaintains switch ZVS closed and switch ZVS open;When valve 34 opens, as described, the plunger 43 is retracted andSWitch ZVSg opens and switch ZVS' closes, Tiirning' new to the controlcircuit in the present i tion, FIG; 3 shows a schematic circuit diagramh'av g the lines numbered for convenience of understanding the operationor the circuit. Five relays, A, C, and E, are provided which operatecorrespondingl lettered sets of contacts in the various lines. Thediiferentsts of contacts are lettered according to the relay whichoperates them, together with a subscript identifying the line in whichthey appear. For xam le, the set of contacts labelled ag is operated byrelay A and iscon-v nested in line 4.

fee

The power supply lines L and L are connected across a suitable supply ofvolt, 60 cycle alternating current.

Line 1 is connected, through fuses 50 and 51, across the power supplylines and includes, in series, a first set of contacts d operated byrelay D, the solenoid coil K and a second set of contacts d operated byrelay D. Normally (i.e., with relay D die-energized) both sets of relaycontacts d are open. A

Line 2 is connected, through fuses 50 and 51, across the power supplylines L and L This line includes, in series, a first setof relaycontacts 2 operated by relay E, the solenoid coil K and a second set ofrelay contacts e operated by relay E. Normally (i.e., with relay Ede-energized) both sets of relay contacts e2 are open.

Line 4 is connected across the power supply lines L and L5 through fuses52 and 53 and a normally-closed emergency stop push button switch 54.Line 4 includes, in series, the previously mentioned limit switch IRS,which is operated'b y the chain-driven cam 32 in FIG. 1=, a set of relaycontacts it, operated by relay A, a set of relay contacts "b operated byrelay B,- and the coil of relay C. Normally (i.e., with relay Ade-crler- 'gized) the relay contacts a; are open. Also, the relaycontacts 5 are normally open (relay B being de-energize'd). Line 3conta'ins the set of relay contacts operated by relay C, connectedacross the series-connected sets of contacts d arid b Contacts normallyare open.

Line 6 is connected in parallel with line 4 and includes, in series, thelimit switch ILS which is operated by the earn 25 on the crankshaft inFIG. I, a set of relay contacts b operated by relay B, and the coilofrelay B. Normally (i.e., with relay B de-ene'rgiZed) the relaycontacts [1 are open.

Line S contains a set of relay contacts as operated by relay A,connected point 55 in line 4, which is between limit switch IRS and theset of relay contacts 11 and poirit 56 inline 6, which is between theset of relay contacts b and the coil ofrelay B. Line 8 is connected inparallel with lines 4 and 6, and includes, :in series, the normallyclosed contacts of the rmr switches 57 and as, the limit switchlLS whichis operated' by the Z6 en the crankshaft in FIG. 1, the switch which isoperated by the second poppet valve 34 in FIG. 1, the switch IYSg, whichis operated by the first pdp'pet vglve 33 in FIG. 1, a set of relaycontacts a operated by relay E, a set of relay contacts d operated byrelay D, a set of relay contacts cg operated by relay C, a set t relaycontacts 11 operated by relay B, and thecoil of relay A. Withtheir-respective relays de energized, contacts eg are normally closed,contacts' ii are normally closed,contacts cg are normally closed, andcontacts b ne normally closed. The contacts c5 and a, of relay C are ofa known construction which provides an oyer'lap betweenthern, such thatthe C, contacts close before the cg contacts are open when relay C isenergized.

Line 7 includes aset of relay contacts ('2 connected between point 56 inline 6 and point 59 in line 8, which is betweentlie sets of relaycontacts d5 and c Line 9 includes a set of relay contacts as connectedacross the relay contacts 5 in line 8'.

Line 9' also includes, separate frorn'the relay contacts a thenormally-open contacts of the run switches 57 and 58. These switchcontacts are connected in series with each other to the power line Lthrough the emergency stop switch 54 and fuse 52;

Line 11 is connected in parallel with lines 4, 6 and 8. It includes, inseries, the limit switch 2R8, which is oper ated by the chain driven cam33 in FIG.- 1, the switch, IVS which is operated by poppet valve33 inFIG. 1, a set of relaycontacts d operated by relay D,- and the coil ofrelay D. Normally with relay D tie-energized, the relay contacts d' areopen. i A

Line 10 includes, in series, a set of relay contacts a operated by relayA and connected to the normally-open contacts of the second run switch58 in line 9, a set of relay contacts b operated by relay [1, and a setof relay contacts c operated by relay and connected to the point 62 inline 11, which is between the set of relay contacts d and the coil ofrelay d. Normally, with their respective relays de-energized, contacts aare closed, contacts b are open, and contacts c are open.

Line 14 is connected in parallel With lines 4, 6, 8 and 11, andincludes, iu'series, the limit switch 2LS operated by cam 27 on thecrankshaft in FIG. 1, the switch 2V S operated by the second poppetvalve 34 in FIG. 1, a set of contacts e operated by relay E, and thecoil of relay E. Normally (i.e., with relay E de-energized) the contactse are open.

I Lines 12 and 13 include the series-connected sets of relay contacts oand 12, which are connected between point 62 in line 11 and point 63 inline 14, which is between the relay contacts e andrelay E.

In FIG. 3, the various sets ofrelay contacts are shown in their normal(relay de-energized) positions. Also, the various cam-operated andvalve-operated switches are shown in their respective states when thecrankshaft is at its 0 (360) position just prior to the beginning of astroke.

Relays B and C in FIG. 3 function as anti-repeat relays, relay A is aset-up relay which conditions the anti-repeat relays for operation, andrelays D and E control the energization of the solenoids K and K; whichcontrol the operation of the pilot valves 36 and 37 for the poppetvalves 33 and 34 in FIG. 1.

In operation, when lines L and L are connected across the power source,the set-up relay A is energized through line 8, all of the switches andrelay contacts in this line being normally closed.

Such energization of relay A causes its contacts a in line 9 to close,thereby" completing a holding circuit which maintains relay A energizedindependent of relay B.

Also, such energization of relay A closes the a contacts in line 4, 5and7 and opens the normally closed a ccntacts in line 10.

Anti-repeat relay B now becomes energized as follows: from power supplyline L through line 8 to the point 59, through the now-closed a contacts(line 7) to point 56 in line 6, and through the coil of relay B to lineL Such initial energization of relay B closes its set of contacts b andthereby completes a holding circuit in line 6 for itself through thenormally closed limit switch 11.8 and now-closed relay contacts b sothat relay B will remain energized independent of the set-up relay A.

The energization of relay B also closes the b contacts in lines 4, 10and 13 and opens the set of contacts h in line 8. The opening ofcontacts 15 does not affect the energization of the set-up relay A atthis time because of the latters holding circuit through contacts a Theenergization of the anti-repeat relay B completes an energizationcircuit in line 4 forthe other anti-repeat relay C, as follows: frompower supply line L through the normally-closed limit switch IRS, theclosed contacts at of the now-energized set-up relay A, and the closedcontacts h, of the now-energized relay B.

Such initial energization of relay C causes its set of contacts 0 inline 3 to close, completing a holding circuit for relay C through limitswitch IRS in line 4 and the now-closed contacts c in line 3. Thisholding circuit maintains relay C energized independent of eithertheset-up relay A or the first anti-repeat relay B.

The energization of relay C also closes the c contacts in lines 1% and12 and opens the 0 line 8. As already pointed out, the construction ofthe relay is such that the c contacts close before the'c contacts open.

, Such opening of the contacts 0 in response to the energization ofrelay C, breaks the energization circuit contacts in through line 8 forthe set-up relay A. Accordingly, relay A becomes de-energized, and itscontacts in lines 4, 5, 7 and 9 openand its contact in line 10 closes.

Because of the opening of contacts a in line 5, the anti-repeat relays Band C are now isolated from each other and each is energized independentof the other. This condition is maintained for the cycle of operation ofthe machine which is to follow.

To recapitulate the operation thus far, when power is applied to thelower lines L and L the set-up relay A is energized and it causestheanti-repeat relays B and C to become energized in sequence. Then theset-up relay A is de-energized and the anti-repeat relays B and C aremaintained energized independent of each other.

The single stroke of the machine is initiated by manually depressing therun push-button switches 57 and 58 in lines 8 and 9. In accordance withaccepted safety practice, these switches are so located on the machineas to require both hands of the operator to be out of the way of themoving parts of the machine. In the illustrated embodiment, theseswitches must be held depressed for almost the entire first half of thecycle of the machine, so that there is no possibility of the operatorremoving his hands to a dangerous position.

It is to be understood, however, that the present invention does notrequire such a two-hand" start control. If desired, a single run switchmay be provided to start the machine, although this is generallyregarded as undesirable from the safety standpoint. In the event that atwo-hand start control is used, it may be of any type desired since thepresent control system is readily compatible with any such arrangement.

The operation of the run switches 57 and 58 completes an energizationcircuit for valve relay D as follows: from power line L through fuse 52and the normally closed emergency stop switch 54, the now-closedcontacts of run switches 57 and 58 in line 9, the normally-closedcontacts a of de-energized relay A, the now-closed contacts b ofenergized relay B. The nowclosed contacts c of energized relay C,through the coil of relay D, and through fuse 53 to the other power lineL Relay E is energized at the same time through the now-closed contactsin line 9 of run switches 57 and 58, the a b and c contacts, and thenow-closed contacts 0 and b of energized relays C and B, respectively.

As a result:

(1) Both sets of relay contacts d in line 1 close;

(2) Both sets of relay contacts 2 in line 2 close;

(3) The normally-closed contacts d in line 8 open;

(4) The normally-closed relay contacts 2 in line 8 open; 1

(5) The normally-open relay contacts d in line 11 close; and

1(6) The normally-open relay contacts e in line 14 c ose.

Solenoid K in line 1 becomes energized from power line L through fuse50, both sets of relay contacts d in line 1, and fuse 51 to power line IAt the same time, solenoid K becomes energized through both'sets ofrelay contacts 2 in line 2.

The energization of solenoids K and K causes the pilot valves 36 and 37in FIG. 1 to close, which open the poppet valves, 33 and 34 admittingair under pressure to the clutch 21 and the brake 24. The brake isthereby released and the clutch is engaged, coupling the drive motor 22to crankshaft 20 so that the crankshaft begins to turn.

At the same time, the retraction of plunger 42, when valve 33 opens,causes switchlVS in line 8 to open and switch 1VS in line 11 to close.Also, the retraction of plunger 43, when valve 34 opens, causes switch2VS inline 8 to open and switch 2V8 in line 14 to close.

It should'be noted that in the present control each of the anti-repeatrelays B and C (which are isolated from each other) has complete controlover the initiation of the stroke of the machine. Thus, if either ofthese relays is not energized, the valve relays D and E cannot becomeenergized to cause the stroke to begin, as just described.

With the stroke having begun in the manner just described, the runswitches 57 and 58 must be held depressed for the first 175 of rotationof the crankshaft. At 175 the limit switches 2R8 and 2L8 are closed bythe chain-driven cam 33 and the crankshaft cam 27, re-

spectively.

The closing of limit switch 2R8 completes a holding circuit through linel]; for relay D as follows: through the now-closed limit switch ZRS, thenow-closed valve switch IYS and the now-closed contacts 4 to the coil ofrelay D. I

The closing of limit switch 2LS completes 'a holding circuit for relay Ethrough line 14 as follows: through the nowclosed limit switch ZLS, thenow-closed valve switch 2VS and the now-closed relay contacts 6 to thecoil of relay E. c Now the run switches 57 and 58 may be released andrelays D and Ewill continue to be energized through their respectiveholding circuits in lines 11 and 14. Such release of these switchescauses their normally-closed contacts in line 8 to reclose.

As indicated in FIG. 2, the limit switches lLS and llLS are opened bythe respective crankshaft cams 25 and26 at about 185 rotation of thecrankshaft.

The opening of limit switch 1LS breaks the holding circuit in line 6 foranti-repeat relay B, so that this relay becomes de-energized.Accordingly, the b relay contacts in lines 4, 6, 1t? and 13 open, andthe set of b relay contacts in line 8 close. Relay B now cannot bere-energized until the set-up relay A is again energized.

The opening of the set of relay contacts is, in response to thede-energization of relay B, isolates the valve relays D and E from eachother. Relays D and E remain independent of each other throughout therest of the stroke.

Should either limit switch ZRS or ZLS have failed to close (at 175), thede-energization of relay B (when switch ILS opens at 185) will cause thecorresponding relay D or E to become de-energized at this time, therebystopping the machine immediately.

Assumin that no such failures have occurred, when the crankshaft hasturned through about 305, the chaindriven cam 32 opens the limitswitchlRS. This breaks the holding circuit through lines 4 and 3 foranti-repeat relay'C and this relay becomes tie-energized. Relay C cannotbecome re-energized until after the set up relay A and the firstanti-repeat relay -B are again energized.

The de-energization of relay C opens the c relay contacts in lines 3, 10and 12 and closes the set of c relay contacts in line 8.

With line 8 broken at the now-open valve switches 2VS and 1VS and at thenow-open contacts e and d of energized relays E and D, the set-up relayA cannot be re-energized at this time.

When the crankshaft has turned through approximately 330 the limitswitch 2R5 is opened by the chain-driven cam 33 and the limit switch ZLSis opened by the crankshaft cam 27.

The opening of limit switch 2R8 breaks the holding circuit for valverelay D through line 11, so that relay D becomes de-energized.

The opening of limit switch 2L8 breaksthe holding circuit through line14 for relay B so that this relay becomes de-energized.

Such de-en'ergization of relay D opens the d relay contacts in line 1and causes solenoid K to become deenergized. v

The de-energization of relay E'opens the a relay contacts in line 2 andcauses solenoid K; to become-deenergized. v n i c The de-energization ofsolenoids K and K results in the opening of the pilot valves 36 and 37and the consequent closing of the poppet valves 33 and 34, therebyshutting off the air supply to the brake 2 4 and clutch 21. The clutchis disengaged and the brake is applied to the crankshaft. The crankshaftcomes to a stop after it has completed 360 rotation, corresponding to afull stroke of the machine.

In addition, the re-closing of valves 33 and 34 causes switch 1V8}, tore-close, switch 1VS to re-open, switch 2VS to re-close, and switch Z VSto re-open. A Now, if the run switches 57 and 58 are notheld depressed,all the switches and relay contacts in line 8 are closed. Accordingly,the set-up relay A will again be energized and the circuit will beconditioned for another single stroke cycle of operation of the machine.This next stroke is initiated by the operator when he depresses both runswitches 57 and 58 and holds them down for the first of rotation of thecrankshaft 20, as previously described. 7

Note, however, that a repeat stroke cannot occur if the operator hasheld the run switches depressed throughout the stroke or has depressedthem again toward the end of the stroke. In either case, the anti-repeatrelays B and C cannot be energized again because the setup relay A willremain de-energized due to line 8 being open, and the valve relays D andE cannot be energized through line 10.

The same result is obtained if the operator attempts to beat the controlby staking down one of the run switches.

The limit switch 1LS is rovided in line 8 to prevent any possibility oftelegraphing (repeated sequential operation) between relays A, B and C.Such telegraphing might take place if the cam-operated limit switchesIRS-and ILS are so operated as to be open simultaneously, which shouldnot happen if their respective operating cams are set properly. However,if this were to happen, in the absence of switch ILS relay A wouldbecome energized through line A and cause relays B and C to becomeenergized in succession, and after the relays are de-ener'gized, thecycle would repeat itself. However, since switch lLS in line 8 will openwhen switch lLS opens, relay A cannot be energized at this time, and theundesired telegraphing is positively prevented.

The present control system provides a pair of indepcndentlyoperatingcontrol components or sub-assemblies for each control function. Asexplained in detail hereinafter, if either component or sub-assembly inany pair fails to operate properly, the machine will stop and a repeatstroke cannot take place. Thus, the system ineludes: V

(a) The pair of anti-repeat relays B and C, which, once energizedinitially, operate independent of each other such that if either failsthe machine will be stopped.

(b) The pair of limitswitches v1L8 and IRS, which are operated indeendently by the Separately driven cams 25 and 32, respectively, tocontrol the anti-repeat relays B and C. If either of these limitswitches, or the mechanism which operates it, fails to operate properly,the machine will be stopped.

(c) The pair of valve-operating relays D and E which, once energizedinitially, operate independent of each other through the last half cycleof the machines operation, such thatif either fails, the machine will bestopped.

(d) The pair of limit switches IRS and 2L8, which are operatedindependently by the separately driven cams 33 and 27, respectively,tocontrol the valve-operating relays D and E. If either of these limitswitches, or the mechanism which operates it, fails'to operate properly,the machine will be stopped.

(e) The pair of solenoid-operated valve and switch sub-assemblies,namely,

. -9 1) Solenoid K pilot valve 36, poppet valve 33 and switches 1VS andIVS and V (2) Solenoid K pilot valve 37, poppet valve 34, and

switches ZVS and 2V8 If any component in either of these sub-assembliesfails to operate properly, the machine will be stopped.

The present circuit is completely foolproof in operation in the eventthat one of the control components (solenoid, pilot valve, poppet valve,valve-operated switch, limit switch or relay) fails to operate properly.A repeat stroke of the machine is possible only in case certain pairs ofthe control components malfunction simultaneously. The probability ofthis happening is so remote as to be virtually non-existent.

MONITORING Moreover, the present control circuit automatically monitorsthe performance of each control component. If any control componentfails, the machine will be stopped automatically and the next cycle ofoperation will be prevented.

Valves The automatic monitoring of the first pilot valve 36 takes placeas follows:

(l) If this valve sticks closed, then the valve-operated switch IVS inline 8 will not close at the completion of the cycle. Consequently, theset-up relay A cannot be again energized, which-is a necessarypreliminary to the opening of the second poppet valve '34 for the nextcycle of operation of the machine.

(2 If this valve sticks open, such as through an internal failure orthrough failure of its operating solenoid K the cycle of operationcannot even begin because it will maintain the first poppet valve 33closed and prevent air from being admittedto the outlet line 23 torelease the brake 24 and engage the clutch 21.

The automatic monitoring of the first poppet valve 33 takes place asfollows:

(1) If this valve sticks open, the valve-operated switch 1VS in line 8will not close at the end of the cycle. Therefore, the set-up relay Acannot again be energized and the second poppet valve 34 cannot beopened to begin the next stroke.

(2) If this valve sticks closed, the cycle cannot begin because aircannot be admitted to line 23 to release th brake and engage the clutch.

The automatic monitoring of the second pilot valve 37 takes place asfollows: I

v (1) If it sticks open, the. valve-operated switch 2VS in line 8 cannotclose at the end of the cycle and the setup relay A cannot bere-energized. Consequently, poppet valve 33 cannot be re-opened to startthe next stroke.

(2) If valve 37 sticks open, through an internal failure of itsoperating solenoid K the cycle of operation of the machine cannot beginbecause the normally-closed poppet valve 34 will prevent air from beingapplied to release the brake 24 and engage the clutch 21.

The automatic monitoring of the second poppet valve 34 takes place asfollows:

(1) If it sticks open, the valve-operated switch ZVS in line 8* cannotclose at the end of the cycle and the set-up relay A cannot again beenergized. Therefore, the first poppet valve 33 cannot be re-opened tobegin the next stroke. 7

(2) If valve '34 sticks closed, it prevents'air from releasing the brakeand engaging the clutch to begin the next stroke of the crankshaft.

Solenoids If either solenoid K or K fails to energize or deenergize atthe proper time, this will cause the respective pilot valve to remainopen or closed, and the monitoring takes place as just described,

10 Valve-operated switches The automatic monitoring of thevalve-operated switches 1VS IVS 2VS and 2VS takes place as follows:

(1) If switch lVS sticks open, the set-up relay A is prevented frombeing again energized for the next stroke to take place.

(2) The same is true if switch ZVS sticks open.

(3) The same is true if switch 1VS sticks closed be cause this meansthat switch IVS would thereby be stuck open.

(4) The same is true if switch ZVS sticks closed because this means thatswitch ZVS would be held open.

(5) If switch IVS sticks closed, then switch 1VS in line 11 will be heldopen and relay D can be energized only if, both run switches 57 and 58are depressed. Therefore, an unintentional repeat stroke of the machinecannot be initiated. And even if the operator should initiate the nextstroke by depressing the run switches 57 and 58, this stroke will bestopped at 185 'when relay B is de-energized.

(6) The same is trueif switch 1VS sticks open of itself.

(7) IfIswitchQVS sticks closed, then switch ZVS in line 14 will beheldopen and relay E can be energized only if both run switches 57 and 58are depressed. Thus, the next stroke can be initated only if it isdeliberately started by the operator, and even then it will be stoppedat 185'.

(8) The same is true if switch ZVS sticks open of itself.

Relays when energized, relays 'D and E cannot be energized through line10 and-thenext stroke cannot take place.

' If relay B fails to operate properly when de-energized, the set-uprelay A cannot be again energized through line 8 at the endof the stroketo condition the circuit for the next stroke to take place.

Similarly, if relay C fails to operate properly when energized, relays Dand E cannot be1energized through line 10 and the next stroke cannottake place.

If relay C fails to operate properly when de-energized, the set-up relayA cannot be energized again through line S at the end of the stroke, sothat the circuit may be conditioned for the next stroke to take place.

If relay D fails to operate properly when energized, the solenoid Kcannot be energized through line 1 and the stroke cannot take place.

If relay D fails to operate properly when de-energized, the set-up relayA cannot be again energized through line 8, which is a necessarypreliminary to the next stroke of the machine.

If relayE fails to operate properly when energized, the solenoid Kcannot be energized through line 2 and the stroke cannot begin.

If relay E fails to operate-properly when de-energized, the set-up relay-A cannotagain be energized through line 8 and the next stroke cannottake place.

7 Limit switches 1 1 holding circuit for relay through line'4.Consequently, relays D and E could not be energized through line for thestroke to occur. It limit switch BIL-S fails to open, relay B willremain energized through line 6 and the. set-up relay A cannot beenergized through line 3 for the next stroke.

If limit switch ILS fails to close, this would break the holding circuitfor relay B through line 6. There fore, relays D and E could not beenergized through line 10 and the stroke cannot take place. 1

If limit switch I'LS fails to close after opening, then the set-up relayA cannot be energized again through line 8 for the next stroke.

If either limit switch 2R8 or 2L8 shouldfail to operate properly, eitherthrough an internal failure or breakage of the chain 29 which drivestheir respective operating the next stroke will b prevented as follows:(1) Failure of switch 2R8 to open will" maintain relay D energizedthrough it holdirig circuit in line 11. Con- Sequently, the set-u relayA cannot again be energized through line 8 for the next stroke to takeplace.

(2) Failure of switch 2RSto close will prevent the holding circuit inline 11 for relay D from being completed and when the limit switch l Lsgopens, ata crankshaft position of about 185, the machine will stopimmediately. i (3) Failure of switch to open will maintain relay Eenergized through its holding circuit in line 14. Therefore, the set-uprelay cannot again be energized through line 8 for the next stroke totake place. a

(4) Failure of switch 2L8 to' close will .prevent the holding circuit inline 14 forrelay E from being completed and when the limit switch lLS inline 6 opens, at a crankshaft position of about 185 lthe machine willstop immediately.

The type of failure of limit switch 2R5 or 2L8 men-- tioned in 2 and 4above is not dan erous, in that it would not result in an unexpectedrepeat stroke of the machine. However, the system does operate tomonitor such a malfunctioning of either of these switches.

VALVE UNIT STRUCTURE The detailed construction of the first pilot valve36 and the first main valve 33 is shown in FIGS-.4 and 4A. 7

plunger carries a resilient insert 74 for engagement with the valve seat75 to block the now or said from the inlet passage 71 down intothechamber 73. The plunger is normally biased doWl'lWtI'd; due to gravityand the bias exerted by a coil spring 76 and the airpressure at theinlet passage 71,- to permit air to flow from the inlet passage 71 downinto chamber 73. As shown in FIG. 4A, an outlet passage 77 leads fromthe bottom of chamber 73 to a passage 78 (FIG. 4) which communicateswith a passage 79 leading into the poppet chamber 80 of the main valve33.

The poppet 81 at its lower end carries a resilient, compressible ring 82for sealing engagement with a valve seat 83 to block the how of air fromthe inlet chamber 84- to' the outlet chamber 85 of the main valve. 7 Astem 86 is connected to the poppet-81 to move therewith. At its lowerend the stem carries a valve element 87 provided with a resilient,compressible ring 88 at its upper face for engagement with a seat 89. Achamber 90 below the valve element 87 communicates with the inletchamber 84 through a passage .91 formed in the body of the valve. Thesurface area of the valve element 8'7 which is exposed to the airpressure inchamber 90 is appreciably less than the surface area of thepoppet 81 which is exposed tothe air pressure in the poppet chamber 80.Accordingly, therefore, when the plunger 72 of the pilot valve is in itsnormal (down) position, the downward force exerted by the air on thepoppet 81 exceeds the upward force exerted by the air on the valveelement 87. Therefore, the main valve is normally closed, as showniil'FIG.'4.

The solenoid K is disposed within the body of the pilot valve 36. Whenthis solenoid is energized it pulls the pilot valve plunger 72upward'until it closes off the inlet passage 71 at the valve seat 75.The air pressure in chamber 73 of the pilot valve and in the poppetchamber of the main valve is relieved through a relief passage 92 (FIG.4A). Normally, this relief passage .is blocked by the insert 93 on thelower end of the pilot valve plunger 72. However; when the plunger ispulled up by the solenoid, the relief passage 92 communicates with thelower end of-the pilot valve chamber 73. v. V

Due to the relieving of theair pressure in the poppet chamber 80, theair pressure acting against the valve element 87 in the main valveforces this valve element and the valvestem 86 and the popp-ethl upward.The air is now free to flow from the inlet chamber 84 of the main valvepast the valveseat 83. to the outlet chamber 85.

The main valve 33 remains open as long'as the pilot valve 36 remainsclosed, which condition is maintained only so long as the solenoid Kremains energized.

The plunger 42, which operates the valve switches IVS and IVS isconnected to the lower end of the stem 86 and projects down through thebottom of the valve casing, a suitable seal 96 being provided to preventair from leaking down around the plunger. The plunger 42 moves in unisonwith the valve stem 86 so that when the main valve is closed the plunger42 is in its extended position below the valve-and when the main valveis open the plunger is in its retracted position.

ALTERNATIVE CIRCUIT-FIG. 5

FIG. 5 .shows an alternative circuit for use in the present system.Here, the functions of the single relay C in FIG. 3 are performed by apair of relays C and F.- This alternative arrangement obviates the needfor an overlap in the operation of two sets of relay contacts, as in 116.3.

In FIG. 5 the coil of relay .F is connected across the power supply inseries with limit switch IRS and the normally-open set of relay contacts0 operated by relay C. I

The coil of relay C is connected to the point 56 in line 6 through thnormally open sets of rela contacts in and'ln. The former set of relaycontacts a (FIG. 3) is omitted. 7

A normally/open set of contacts e operated by relay C, is connectedbetween the juncture of the relay contacts 41 and b and the juncture ofthe set of relay contacts o and relay F. Thus, a holding circuit forrelay C is provided through limit switch IRS and the sets of relaycontacts c andc In lines 10 and 12, the former relay contacts c and C12(FIG. 3) are replaced by relay contacts fin and f operated by relay F.

In line 8 the energization circuit for the set-up relay A includes anormally-closedjset of contacts i operated by relay F. The normally-openset of relay contacts a' is connected across the series-connected setsof contacts c and b in line 8.

In all other respects; the FIG. 5 circuit is identical to FIG. 3. V y

In the operation of the FIG. 5 circuit, when the set-up relay A and thefirst anti-repeat relay B are energized, relay C becomes energizedf'through the a and b con- I3 tacts. Such energization of relay C causesits contacts and 0 to close, so that relay F becomes energized.Accordingly, the relay contacts of f andf close, so that valve relays Dand E become energized.

It will be noted that the initial energization of relay C completed aholding circuit for this relay through the limit switch IRS and therelay contacts c and 0 Accordingly, relay C will remain energizedthrough this holding circuit until the limit switch IRS is opened. Also,relay F will remain energized through limit switch 1RS and relaycontacts 0 It will be apparent that in this alternative arrangernent therelays C and F are energized in sequence so that the holding circuit forrelay C is completed a finite period of time before the set of contactsf in line 8 opens to de-energize the set-up relay A. Therefore, there isno need to provide an overlap between the 0 contacts, which provide thisholding circuit for relay C, and the contacts i which cause relay A tobe deene'rgized.

' In other respects, the operation of the FIG; 5 circuit is identical toFIG. 3.

PREFERRED CIRCUIT-FIG. -6

A still further embodiment of the circuit in the present system is showninFlG. 6. This is the preferred embodiment for a number of practicalreasons. In the FIGURE 6 circuit the set-up relay A is provided withsets of contacts a'-, and a' for energizing the anti-repeat relays B andC,re spectively. When the coil of relay A is energized it closes thecontacts a-, to initially energize the coil of relay B and at the sametime it closes the contacts a to initially energize the coil of relay C.Following their initial energization in this manner, the coil of relay Bcompletes a holding circuit for itself through its contacts b and thecoil of relay C completes a holdingci-rcuit for itself through itscontacts c'.;,. It Will be noted that in this embodiment the' relays Band C are energized simultaneously, rather thansequentially, and arecompletely independant and isolated from each other at all times.

This arrangement completely eliminates. a difiiculty which might ariseifs'evere contact bounce should happen to occur at the holding contactsc of relay C in the FIG. 3 circuit, or at the corresponding holdingcontacts foreither relay B or relay C in FIG. 5. v In either case thesituation might arise that the holding contacts for either anti-repeatrelay B or C might bounce open just at the time that the set-up relay Ais being de-energized by the breaking of its energization circuit inline 8. In such case, the stroke of the machine could not be initiatedby depressing the frun switches 57 and 58, and the set-up relay would belocked out so that it could not again be energized to set up theanti-repeat relays preliminary to the operation of the A, the followingwould happen: Relay C would become de-energized since contacts'c and a,are now open. Therefore, contacts ,0 would again close. However, relay Bwould remain energized (through its holding contacts b and its bcontacts would remain open. With the b and u contacts both open there isno possibility of automatically re-energizing relay A to again set'upjthe anti-repeat relays B and C. And with relay C de-energized, onecannot initiate a stroke of the machine by depressing the run switches57 and 58. As long as this condition prevails, the entire controlcircuit and-the machine will be stalled.

A similar difiiculty would mouth the event of severe contact bounce ;atany of the other holding contacts for t the anti-repeat relays in eitherFIG. 3 or FIG. 5.

, This diificulty cannot arise intheFIG. 6 circuit .because theenergization of the anti-repeatrelays does not 14 result in theimmediate de-energization of the setup relay A. Rather, the set-up relayA retains its holding circuit through its a contacts until the runswitches.57 and 58 are depressed. Accordingly, the occurrence of anysevere contact bounce at the holding contacts for either anti-repeatrelay B or C would not lock out the set-up relay A.

In addition to eliminating the problems attendant to contact bounce atthe holding contacts of either antirepeat relay, the circuit of FIGURE 6is inherently safer because of the fact that the anti-repeat relays Band C are independent of eachother and isolated at all times.

Also, in the FIGURE 6 circuit each relay has just four sets of contacts,so that all relays in the control panel may be identical to each other.

The circuit of FIGURE 6 requires one less relay in the panel than theFIGURE 5 circuit, while at the same time avoiding theneed foroverlapping contacts in the second anti-repeat relay, as in FIGURE 3.

Also, it will be noted that the double pole limit switch ILS and 1LS inthe circuits of FIGURES? and 5 is replaced by a single pole switch 1LS'in the circuit of FIGURE'6.

Except for these changes the circuit of FIGURE 6 operates the same asthe circuits of FIGURES 3 and 5, the correspondingly designated elementsoprating in the same .manner as in FIGURES 3 and 5. The sequence ofoperation of the limit switches IRS, 2R8, 1LS and 2L8 is the same as inFIG. 2.

While the preceding description and the accompanying drawings aredirected to the three diflerent embodiments of the present invention, itis to be understood that various modifications, omissions andrefinements which depart from the disclosed embodiments may be adoptedwithout departing from the spirit and scope of this invention.

For example, in the fluid control unit the plunger-operated switches IVSand 1VS may be replaced by pressure-operated switches connected intheair line after the first main valve 33 and ahead of the second'mainvalve 34 so as to respond to the operation of the first main valve only.

This application is a continuation-in-part ofour copending application,Serial No. 738,107, filed May 27, 1958, now abandoned.

Having thus described our invention, we claim:

1. A single cycle control system for a machine in which fluid pressurecontrols the starting and stopping of the machine,- said systemcomprising: a pair of valves connected to control said fluid pressuresuch that the machine is stopped if either valve is closed, a pair ofvalve relays operable independent of one another to control therespectivevalves individually, a pair of anti-repeat relays operable toenergize the valve relays initially to cause the respective valves toopen, a pair of separate holding circuits connected individually to therespective valve relays to maintain the latter energized independent ofeach other following their initial energization, a first pair of limitswitches connected respectively in said holding circuits and operableseparately and independent of one another by the machine toward the endof the latters cycle of operation to open the respective holdingcircuits individually independent o'f-one another to de-energize therespective valve relays individually independent of one another, and asecond pair of switches connected respectively in said holding circuitsand operable individually independent of one another to close inresponse to the opening of the respective valves. Y 2. The controlsystem of claim 1, wherein there are provided'a pair ofseparate limitswitches connected to control individually and independent of oneanother the energization of the respective anti-repeat relays andoperable separately andindependent of one another by the machine duringits cycle of operationto de-energize the respective anti-repeat relaysindividually independent of one another. j

3. In a single cycle control system for a machine in which fluidpressure controlsthe starting and stopping of the machine, theimprovement which comprises: a pairof separate valve units connected tocontrol said fluid pressure such that-the machine is stopped if eithervalve unit is closed, a pair of valve relays which operate said valveunits to stop the machine if either valve relay is tie-energized, a pairof anti-repeat relays which control the initial energization of saidvalve relays, a first pair of separate limit switches connectedrespectively to said valve relays and operable individually independentof one another to control the energization of said valve relays afterthey have been energized initially, and a second pair of separate limitswitches connected respectively to said anti-repeat relays and operableindividually independent of one another to control the operation of saidanti-repeat relays, each limit switch in each pair being operablethrough its cycle for each cycle of operation of the machine. 7

4. In a single cycle control system for a machine, the combination of apair of control devices which when actuated start the cycle of operationof the machine, a pair of anti-repeat devices operable to actuate saidcontrol devices for starting the cycle of operation of the machine, apair of separate stopping limit switches which control the-operation ofsaid control devices individually independent of one another followingtheir actuation by said anti-repeat devices and which are operatedindividually independent of one another during each cycle of operationof the machine to disable said control devices, and a pair of separateanti-repeat limit switches which control the operation of saidanti-repeat devices individually independent of one another and whichare operated individually independent of one another during each cycleof operation of the machine to disable said antirepeat devices fromagain actuating said control devices, thereby preventing a repeatcycleof operation of the machine.

5. A single cycle control system for a machine comprising: a pair ofseparate control means which both con trol the starting and stopping ofthe machine; a pair of control devices operable to control individuallythe operation of the respective control means; a pair of anti-repeatdevices connected to control jointly the initial operation of saidcontrol-devices; a first pair of limit devices connected to establishseparate lines for said control devices to maintain the lattersoperation independent of each other and independent of said anti-repeatdevices following their operation initially by said anti-repeat devices;means for operating said anti-repeat devices initially; a second pair oflimit devices connected to establish separate lines for said anti-repeatdevices to maintain the latters operation independent of each other and'independent of said last-mentioned means following their initialoperation by said last-mentioned means; a first pair of control meansoperable individually during each stroke of the machine to actuateindividually and independent 7 of one another the limit devices of saidsecond pair to disconnect said lines which maintain the operation ofsaid anti-repeat devices; and a second pair of separate control meansoperable individually during each stroke of the machine to actuateindividually and independent of one another the limit devices of saidfirst pair to disconnect said lines which maintain the operation of saidcontrol devices. a

6. A single cycle control system for a machine in which fluid pressurecontrols the starting and stopping of the machine, said control systemcomprising: a pair of valve means connected to jointly control saidfluid pressure; a pair of separate valve control means operable tocontrol individually the operation of the respective valve means; a pairof anti-repeat devices connected to control jointly the initialenergization of said valve control means; a first pair of limitswitches'connected to provide separate holding circuits for said valvecontrol means to maintain the latter energized independent of each otherand independent of said anti-repeat devices following their initialener'gization; means for'energizing said antirepeat devices initially; asecond pair of limit switches connected to provide separate holdingcircuits for said anti-repeat devices to maintain the latter energizedindependent of each other and independent of said lastmentioned meansfollowing their initial energization; a first pair of separate controlmeans operable individually during each stroke of the machine to actuateindividually and independent of one another the limit switches of saidsecond pair to tie-energize said anti-repeat relays; and a second pairof separate control means operable individually during eachstroke of themachine to actuate individually and independent of one another therespective limit switches of said pair to de-energize said valve controlmeans.

7. A single cycle control system for a machine in which a fluid pressureline controls the operation of the machine, said control systemcomprising: a pair of valve means connected in series in said line tojointly control the operation of the machine independent of one another;a power source; a'pair of solenoids operable respectively to control theoperation of said pair of valve means individually, a first pair ofindividual circuits connecting said solenoids individually to said powersource independent of each other, separate sets of relay contactsconnected in said circuits to control the energization of the respectivesolenoids individually from vthe power source; a pair of valve operatingrelays which operate said sets of relay contacts individuallyindependent of each other, a second pair of individual circuitsconnecting said valve-operating relays individually to said power sourceindependent of each other, a first pair of separate limit switchesconnected individually in said last-mentioned circuits to control theenergization of said valveoperating relays individually; a pair ofanti-repeat relays, a third pair of individual circuits connecting saidantirepeat relays to said power source independent of each other, asecond pair of separate limit switches connected individually in saidlast-mentioned circuits to control the energization of said anti-repeatrelays individually from the power source; means for energizing saidanti-repeat relays initially from the powerfsource prior to thebeginning of a' stroke of the machine; an additional circuit forenergizing'both said valve-operating relays independent of said secondcircuits, operator-controlled normallyopen switch means" connected insaid additional circuit, individual sets of relay contacts connected inadditional circuit and operable respectively independent of one anotherby said anti-repeat relays to complete said additional circuit toenergize the valve-operating relays initially after the anti-repeatrelays have been energized when said operator-controlled switch means isclosed; a first pair of separate control members operable individuallyindependent of one another during each stroke of the machine to actuateindividually and independent of one another the respective limitswitches of said second pair to de-energize said anti-repeat relaysindividually independent of one another; and a second pair of separatecontrol members operable individually independent of one another duringeach stroke of the machine to actuate individually and independent ofone another the respective limit switches of said first pair tode-energize said valve-controlling relays individually independent ofone another. i 8. The control system of claim 7 wherein said energizmgmeans for the anti-repeat relays comprises a set-up relay operable whenenergized to energize said anti-repeat relays independent of each other,and wherein there is provided means for maintaining said set-up relayenergized 7 independent of said antirepeat relays until saidoperatorcontrolled switchmeans is closed.

9. A single cycle control system for a machine in h h id pressurecontrols the operation of the machine yqqt lfiysterncomprising; a pairof valve means 1? connected to control jointly said fluid pressureindependent of one another; a pair of electrical control devices whichcontrol the respective valve means individually; at first pair ofindividual separate circuits for connecting said electrical controldevices individually to a power source independent of each other,separate switch means connected in said circuits to control theenergization of said electrical control devices individually from thepower source; a first pair of electrical operating devices which operatesaid switch means individually independent of one another, a second pairof individual circuits for con necting said first operating devicesindividually to the power source independent of each other, a first pairof separate limit switches connected in said last-mentioned circuits tocontrol the energization of said first operating devices individuallyfrom the power source; a second pair of electrical operating devices, athird pair of individual circuits for connecting said second operatingdevices individually to the power source independent of each other, asecond pair of separate limit switches connected individually in saidlast-mentioned circuits to control the energization of said secondoperating devices individually from the power source; means forenergizing said second operating devices initially prior to thebeginning of a stroke of the machine; an additional circuit forenergizing both said first operating devices independent of said secondcircuits, operator-controlled switch means connected in said additionalcircuit, a plurality of individual switch means connected in saidadditional circuit and operable respectively by said second operatingdevices to complete said additional circuit to energize said firstoperating devices initially after said second operatng devices have beenenergized when said operator-controlled switch means is closed; a firstpair of separate control members operable individually independent ofone another during the stroke of the machine to actuate individuallyindependent of one another the respective limit switches of said secondpair to de-energize said second operating devices individuallyindependent of one another; and a second pair of separate controlmembers operable individually independent of one another during thestroke of the machine to actuate individually independent of one anotherthe respective limit switches of said first pair to de-energize saidfirst operating devices individually independent of one another.

10. A fluid control unit for a machine in which fluid pressure controlsthe operation of the machine, said fluid control unit comprising: afirst main valve having an inlet forconnection to a fluid pressure lineand having an outlet, a second main valve having an inlet connected tothe outlet of the first main valve and having an outlet for connectionto an outlet line, a normally-open first pilot valve having an inletconnected ahead of the first main valve and having an outlet connectedto said first main valve to normally maintain the latter closed, meansfor selectively closing said first pilot valve to permit the first mainvalve to open, a normally-open second pilot valve having an inletconnected ahead of said first main valve and having an outlet connectedto said second main valve to normally maintain the latter closed, and

means for selectively closing said second pilot valve t permit thesecond main valve to open.

11. In a single cycle control system for a machine in which fluidpressure controls the operation of the machine, the improvement whichcomprises: a pair of separate valves each connected to control saidfluid pressure, means controlling the operation of said valves to openeach valve at the beginning of each cycle of the machine and to closeeach valve at the end of each cycle of the machine, energization meanscontrolling the operation of said controlling means, and a pair ofseparate switches connected in said energization means so that eachindependently controls the operation of said controlling means, saidswitches being positioned respectively to be opened and closedindependent of one another by said valves for each cycle of the machineso that upon failure of either valve or either switch to operateproperly said controlling means will be ineflective to operate the othervalve to cause the next stroke of the machine to take place. 7

12. In a single cycle control system for a machinein which fluidpressure controls the operation of the machine, the improvement whichcomprises: a pair of separate valves connected to control said fluidpressure such that the machine is stopped if either valve is closed, apair of separate operating devices operable when energized to cause therespective valves to open independent of one another at the beginning ofeach cycle of the machine and operable when de-energized to cause therespective valves to close independent of one another at the end of eachcycle of the machine, means for energizing said operating devicesinitially to cause the valves to open to initiate a stroke of themachine, a pair of separate holding circuits for the respectiveoperating devices to maintain the latter energized independent of oneanother following their initial energization, a pair of separatenormally-open swtches positioned to be closed respectively by the valvesindependent of one another when the valves open at the beginning of eachstroke of the machine and to be opened individually independent of oneanother by the valves when the latter close at the end of each stroke ofthe machine, said switches being connected respectively in said holdingcircuits so that upon failure of either switch to close the respectiveholding circuit will be broken to de-energize the respective operatingdevice andcause the respective valve to close to stop the machine.

13. In a single cycle control system for a machine having a fluidpressure line for controlling the operation of the machine, theimprovement which comprises: a pair of separate normally-closed mainvalves connected in said line to control the flow of fluid therethroughsuch that the machine is stopped if either valvevis closed, a pair ofseparate normally-open pilot valves for'operating the respective mainvalves separately independent of one another, each of said pilot valveshaving its input connected to said line ahead of both main valves andhaving its output connected to the respective main valve to normallymaintain the latter closed, a pair of separate solenoids for closing therespective pilot valves individually independent of one another to openthe respective main valves, control means for controlling theenergization of both said solenoids to energize and de-energize eachsolenoid for each stroke of the machine, an energization circuit forsaid control means which controls the latters operation, and a pair ofseparate normally-closed switches connected in said energization circuitto control individually and independent of one another the operation ofsaid control means, said switches being positioned to be openedindividually independent of one anotherjby the' respective main valvesat the beginning of each stroke of the machine when both solenoids areenergized to close the respective pilot valves which open the respectivemain valves, each of said switches being held open by the respectivemain valve as long as the latter remains open so that upon failure ofeither main valve to closeat the end of the stroke of the machine whenthe solenoids are de-energized said control means will be ineifective toreenergize the solenoids so that the other main valve,

will be reopened for the next stroke of the machine to take place, eachof said switches being operable to close when the respective main valvecloses.

14. In a single cycle control system for a machine having a fluidpressure line for delivering fluid to start the stroke of the machine,the improvement which comprises: a pair of separate normally-closedvalves connected in said line to control the flow of fluid therethroughsuch that the machine is stopped if either valve is closed, meanscontrolling the operation of both of said valves to open and close eachvalve for each cycle of the machine, an energization circuit for saidcontrolling means which controlsv the. latters. operation, and a pair ofseparate. normally-closed switches. connected in said energizationcircuit. so that; each independently controls the. operation. of said.controlling means, said switches being positioned to be openedseparately independent. of one, another by the respective. valves whenthe latter open at the. beginoi each stroke of the. machine. andv to.remain. open as long as the respective valve remains open so thatupoufailure of either valve to close or either switch to close at the. endof said stroke. of the machine said controlling means willbe ineffectiveto re-open the other valve for the next stroke of the machine to. takeplace, each of said switches being operable to close when the respectivevalve: closes.

15 In a single cyclecontrol system for a machine in which fluid pressurecontrols the starting and stopping of the machine, the improvement whichcomprises: a pair of normally-closed valves connected to control said.fluid pressure such that the machine is stopped it either valve isclosed, control means operative when energized to open said valves, aset-up relay, a circuit for energiza ing, said set-up relay, meansoperable after the energization and de-energizati-on of said set-uprelay for energizing said control means to cause the valves to open, anda pair of separate normally-closed switches connected in saidenergization circuit for the. set-up relay to control the lattersenergization, said switches being positioned .to, he opened individuallyindependent of one another by the respective valves when the latter openat the beginning of each stroke of the machine, each of said switchesbeing held open by the respective valve independent of the other valveas long as the respective valve remains, open to thereby maintain theset-up relay de-energized to prevent a repeat stroke of the machine,each switch closing when the respective valve closes at the end of eachstroke of the machine.

16. In a single cycle control system for a machine in which fluidpressure controls the starting and stopping of the machine, theimprovement which comprises: a pair of valve means connected to controlsaid fluid. pressure, a pair of relays operable for each cycle of themachine to open and close the respective valve means individuallyindependent of one another, means for energizing the relays initially toopen the respective valve means to start the machine, a pair of separateholding circuits connected to the respective relays to maintain thelatter' separately energized independent of each other following theirinitial energization, and a pair of switches connected respectively insaid holding circuits and operated individually independent of oneanother by the respective valve means to close when the respective valvemeans opens at the beginning .of each cycle of the machine to therebycomplete the respective holding circuits for the relays, each of saidswitches closing when the respective valve means closes at the end ofeach cycle of the machine.

17. In a single cycle control system for a. machine in which fluidpressure controls the starting and stopping of the machine, theimprovement which comprises: a pair of valve means connected to controlsaid fluid pressure, a

pair of relays operable for each cycle of the machine to open and closethe respective valve means separately independent of one another, meansfor energizing the relays initially to open the respective valve meansto start the machine, a pair of separate holding circuits connected tothe respective relays and operable to maintain the relays separatelyenergized independent of each .other following their initialenergization, and .a pair of separate limit switches connectedrespectively in said holding circuits and each operable through itscycle separately during each stroke of the machine to open said holdingcircuits and tie-energize the respective relays to stop the machine atthe end of said stroke.

'18. The combination of claim 17, wherein there are provided a pair ofswitches connected respectively in said holding circuits and operatedindividually by the respecspace ta 2Q tive valve means. to close. whenthe respective valve means. opens at the beginning of. each cycle of;the ma hine and to open. when the respective valve means closes at theend. ot each cycle of. the machine- 19. In a. single cycle controlsystem for a machine having control means for starting, and stopping themachin the improvement which comprises; a pairof electrical controldevices each. operable. through its. y le. f r e cycle. of operation,of. the machine to control the op -ration. of said. control means, meansfor ini i lly energizing said. devices to cause. the machine o start. astroke, a p of separate hol ing circuits connected to the pe i devicesand operable to maintain the. devices separately energized independentvof one another following their initial energization, and apair ofseparate limit switches. connected. respectively in said, holdingcircuits and each operable separately through its cycle during eachstroke of the machine to open the. respective holding circuitde-energize the respective device to cause the machine to stop at theend of its, stroke.

20. In a single cycle control system, for a machine in which fluidpressure controls the starting and stopping of the machine, theimprovement which comprises: a pair of separately normallyclosed valvesconnected to control said fluid pressure such that the machine isstopped if either valve is, closed, a pair of separate relays eachoperable through its cycle for each cycle. of operation of th machine toopen and close the respective Valves individually independent of, oneanother, means for energizing said relays initially to open therespective valves to initiate a stroke of the machine, a pair ofindividual holding circuits operative to maintain the respective relaysseparately energized independent of one another -lollowing their initialenergization, a pair of separate limit switches connected respectivelyin said, holding circuits to control independently the. continuedenergization of the respective relays, each of said limit switchesclosing for each stroke oi the machine, and a pairof separate controlmembers operable individually hy the machine during each stroke to openthe respective limit switches separately independent of one another tostop the machine at the end of said stroke.

21. In a single cycle control system for a machine having control meansfor starting and stopping the machine, the improvement which comprises:a pair of separate relays operable jointly when both are energized toactuate said control means to start the machine and operableindividually when either is de-energized to actuate said control meansto stop the machine, means for initially energizing bothfisaid relaysfor each stroke of the machine to cause the machine to start a stroke, apair of separate holding circuits connected to the respective relays andoperable to maintain the relays separately energized independent of oneanother following their initial energization, means for opening saidholding circuits separately independent of one another to de-energizethe relays at the completion of each stroke of the machine, and a pairof separate sets of contacts operated respectively by the relays andconnected to control the operation of said initial energizing means suchthat uponfailure-of either relay to be de-energized' at the completionof the stroke of the machine said initial energizing means will berendered ineffective to energize both relays to initiate the next strokeof the machine. 7

22. The combination of claim 21, wherein said means for opening saidholding circuits for the relays comprises a pair of separatenormally-closed limit switches connected respectively in said holdingcircuits, and a pair of separate means operated individually by themachine during its stroke to open the respective limit switches andthereby de-energize the respective-relays.

23. In a single cycle'control system for a machine having means forcontrolling the starting and stopping of the machine, the improvementwhich comprises: a pair of anti-repeat devices each operable through itscycle for anoint? each cycle of operation of the machine to control theoperation of said controlling means, means for operating both saiddevices prior to the beginning of a stroke of the machine, and means formaintaining the operation of said devices independent of each otherafter they have been initially operated.

24. The combination of claim 23, wherein said lastmentioned means isrendered operative in response to the initial operation of said devices.

25. In a single cycle control system for a machine having means forcontrolling the starting and stopping ofthe machine, the improvementwhich comprises: a pair of anti-repeat relays each operable through itscycle for each cycle of operation of the machine to control theoperation of said controlling means, a set-up relay, circuit meansoperable by the set-up relay to energize said anti-repeat relaysinitially prior to the beginning of each stroke of the machine, andmeans operable in response to the energization of said anti-repeatrelays to complete separate holding circuits for said anti-repeat relayswhich maintain the anti-repeat relays separately energized independentof each other following their initial energization.

26. The combination of claim 25, wherein there are provided a pair oflimit switches connected respectively in said holding circuits andoperable separately independent of one another during each stroke of themachine to open said holding circuits separately independent of oneanother and dc-energize the respective anti-repeat relays.

27. In a single stroke control system for a machine having means forcontrollingthe starting and stopping of the machine, the improvementwhich comprises: a pair of anti-repeat relays each operable through itscycle for each cycle of operation of the machine to control theoperation of said controlling means, a set-up relay, an initialenergization circuit which includes contacts oper' ated by saidanti-repeat relays, circuit means operable to energize the anti-repeatrelays independent of each other in response to the initial energizationof the set-up relay, a holding circuit for maintaining the set-up relayenergized independent of the anti-repeat relays following the lattersenergization, and operator-controlled means for starting the machinefollowing the energization of the anti-repeat relays and for breakingsaid holding circuit to tie-energize the set-up relay.

28. The control system of claim 27 wherein there are provided a pair ofseparate holding circuits for maintaining the anti-repeat relaysseparately energized independent of one another following the startingof the machine, a pair of separate normally-closed limit switchesconnected respectively in said last-mentioned holding circuits, and apair of separate control means operable individually during the strokeof the machine to open said limit switches individually independent ofone another and dc-energize the respective anti-repeat relaysindividually independent of one another.

References Cited in the file of this patent UNITED STATES PATENTS2,302,838 Bundy Nov. 24, 1942 2,471,505 Winther May 31, 1949 2,636,581Bitler Apr. 28, 1953 2,794,523 Cortelli et a1. June 4, 1957 2,848,087Simson et a1. Aug. 19, 1958 2,886,155 Hadley May 12, 1959 UNITED STATESPATENT OFFICE CERTIFICATE OF CORRECTION Patent No $004,647 October 17, I1961 Everett H, Andrus et al.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 3 line 68 after "C insert D Column 5 line 4, for "relay 10" readrelay B 3 line 5 for "relay 0" read relay C ---3 line 7,, for "relay dread relay D --3 column 9 line 55 before "of", first occurrence, insertor failure column 11, line 55 for "said" read air column 13 line 2,; for"'01" read e 5 column 14 line 26,, for "oprating" read operating column17 line 32 for "operatm read operating column 2O line 24, for"separately" read separate Signed and sealed this 10th day of April1962.

(SEAL) Attest:

ERNEST WI, SWIDER DAVID L. LADD Attesting Officer Commissioner ofPatents I

